An electrode portion provided in a semiconductor device has to be formed thicker according to the recent trend of a larger current capacity and a higher speed. As a result, the number of processes in manufacturing a semiconductor device increases if a rewiring technique is used to thicken the electrodes after the semiconductor element is formed. In this case, an unstable (reactive and active) metal of the electrode is exposed to ambient conditions, erosion easily occurs due to humidity in the ambient air, and there is a fear of deteriorating the reliability of the device. Therefore, when an electrode portion is formed using copper (Cu) or the like, a follow on manufacturing process of covering the surface of the electrode portion with metal (Au) or the like is employed.